A triple truck bomb attack claimed by Islamic State in northeastern Syria killed at least 50 people and wounded 80 others, a spokesman for the Kurdish militia that controls the area said on Friday.

The town in the northeastern province of Hasaka is controlled by the Kurdish YPG militia, which has been battling Islamic State with the support of U.S.-led air strikes.

Kurdish fighters have advanced against the militants in the last few weeks in Hasaka, notably taking over the town of al Houl backed up by a U.S.-backed rebel alliance that includes the YPG.

The three blasts, carried out by at least two suicide bombers, struck outside a hospital, at a marketplace and in a residential area in the town of Tel Tamer late on Thursday, the YPG’s Redur Xelil said via an internet messaging service.

“There is massive destruction in the town and the number killed is between 50 and 60, all of them civilians,” he said.

Islamic State later said in an online statement that three of its fighters driving three separate vehicles had detonated the suicide bombs targeting “bases” belonging to Kurdish fighters.

Earlier the Britain-based Syrian Observatory for Human Rights gave a death toll of at least 22 people in the attack, saying that number was likely to increase.

The Observatory said one of the bombs exploded near a health centre and another near a vegetable market. It said there was “confirmed information” about casualties among the Kurdish internal security force, known as the Asayish.

The YPG has been the most effective partner on the ground in Syria for the U.S.-led coalition that is fighting Islamic State. In October, it became part of the new U.S.-backed alliance, called the Democratic Forces of Syria.